The present invention relates generally to a jack assembly, and more particularly to a jack assembly having an integrated pressure relief assembly.
Various types of jack assemblies are used in a wide array of settings; however, in most circumstances, the jack assemblies are configured to perform a generally similar function of providing an axial force. For example, many automotive-style jack assemblies are arranged between the ground and a vehicle to be lifted. Actuating the jack assembly results in the vehicle being raised relative to the ground, and de-actuating the jack assembly results in the vehicle being lowered.
Mechanical and material limitations of jack assemblies require that each jack assembly has a maximum load rating, that is, a particular jack assembly is designed and configured to repeatedly provide a certain amount of axial force. Exceeding the maximum load rating of a jack assembly may result in damaging the jack assembly (e.g., degrading internal seals, deforming portions of the jack assembly, and the like).
As one example, column-type portable vehicle lifts incorporate a caster jack assembly that urges a caster wheel into engagement with the ground to aid in transporting the lift. However, the maximum load rating of the caster jack assembly is significantly lower than the operating load of the vehicle lift. As a result, if the caster jack assembly is inadvertently left in the extended or engaged position while the vehicle lift is used to support a vehicle, the load transferred to the caster jack assembly may result in damage to the caster jack assembly. Other scenarios commonly arise in which the load placed on the jack assembly exceeds the maximum load rating of the jack assembly, therefore degrading or damaging the components of the jack assembly.
To address this potential issue, some jack assemblies incorporate an external pressure relief valve on a hydraulic cylinder that is used to provide the pressurized fluid to extend the jack assembly. If the pressure in the jack assembly exceeds a certain level, the pressure relief valve allows fluid back into the hydraulic cylinder, thus retracting the jack assembly and minimizing potential damage. However, this external tank-valve arrangement is cumbersome and complex.
In light of at least the above considerations, a need exists for an improved jack assembly having an integrated pressure relief assembly.